Protoplanetary disk formation from the collapse of a prestellar core

TL;DR

This study uses advanced 3D MHD simulations with radiative transfer to model the formation of protoplanetary disks from prestellar core collapse, revealing detailed dynamics, turbulence distribution, and magnetic effects consistent with observations.

Contribution

It presents the first comprehensive 3D MHD simulation of disk formation from prestellar cores including ambipolar diffusion and radiative transfer, bridging the gap between collapse and disk development.

Findings

The formed disk matches observations of class-0 young stellar objects.

Mass flux onto the star is mainly from the envelope, not through the disk mid-plane.

Outer disk regions are highly turbulent, inner regions are relatively quiescent.

Abstract

While it is generally accepted that the magnetic field and its non-ideal effects play important roles during the stellar formation, simple models of pure hydrodynamics and angular momentum conservation are still widely employed in the studies of disk assemblage in the framework of the so-called "alpha-disk" model due to their simplicity. There has only been a few efforts trying to bridge the gap between a collapsing prestellar core and a developed disk. The goal of the present work is to revisit the assemblage of the protoplanetary disk (PPD), by performing 3D MHD simulations with ambipolar diffusion and full radiative transfer. We follow the global evolution of the PPD from the prestellar core collapse for 100 kyr, with resolution of one AU. The formed disk is more realistic and is in agreement with recent observations of disks around class-0 young stellar objects. The mass flux arriving onto the disk and the radial mass accretion rate within the disk are measured and compared to analytical self-similar models. The surface mass flux is very centrally peaked, implying that most of the mass falling onto the star does not transit through the mid-plane of the disk. The disk mid-plane is almost dead to turbulence, whereas upper layers and the disk outer edge are very turbulent. The snow-line is significantly further away than in a passive disk. We developed a zoomed rerun technique to quickly obtain a reasonable disk that is highly stratified, weakly magnetized inside, and strongly magnetized outside. During the class-0 phase of PPD formation, the interaction between the disk and the infalling envelope is important and ought not be neglected. Accretion onto the star is found to mostly depend on dynamics of the collapsing envelope, rather than the detailed disk structure.